Integrated voice mail system for CDMA network

ABSTRACT

A voice mail system is provided in a CDMA wireless telephone system in which a base station controller (BSC) stores, in a encoded format, voice data transmitted by a wireless telephone to a receiving telephone, either wireless or fixed telephone, when the receiving telephone does not &#34;pick up&#34;. Also, the base station controller encodes and then stores voice data that is transmitted by a fixed telephone to a wireless telephone when the wireless telephone does not &#34;pick up&#34;. In either case, to retrieve voice mail the intended recipient can access the voice mail from a fixed telephone, in which case the voice mail is decoded at the BSC and then sent to the fixed telephone via a landline. Alternatively, the intended recipient can access the voice mail from a wireless telephone in the system, in which case the voice mail is not decoded at the BSC, but is transmitted directly to the wireless telephone, where the message is decoded. In any case, the voice mail undergoes only a single encoding/decoding process, thereby improving the sound quality of the retrieved voice mail messages compared to systems in which tandem vocoding occurs.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to wireless telephone systems,and more particularly to voice mail systems for CDMA wireless telephonesystems.

II. Description of the Related Art

Voice mail systems are ubiquitous in modern telephone systems, includingwireless telephone systems. In the wireless telephone context, however,current voice mail systems can degrade recorded messages, because therecorded messages are encoded and decoded multiple times.

More particularly, in the context of code division multiple access(CDMA) wireless telephone systems, a transmitting telephone encodesvoice signals using a vocoder, prior to transmitting the signals overthe air. A preferred CDMA system is described in U.S. Pat. Nos.4,901,307 and 5,103,459, both of which are assigned to the same assigneeas is the present invention and both of which are incorporated herein byreference. Also, a preferred vocoder is disclosed in U.S. Pat. No.5,414,796, which is also assigned to the same assignee as is the presentinvention and which is incorporated herein by reference.

When a person attempts to call a wireless station user from a landlinetelephone, the call is routed through a public switch telephone network(PSTN). The PSTN connects the call to a base station controller (BSC)which controls the operation of a plurality of base stations that servea common geographic area. When it receives the call from the PSTN oranother wireless telephone, the BSC determines whether the recipientwireless telephone is currently registered with any base station. If thewireless telephone is not registered (or it is registered but it doesnot pick up), the call is directed to a voice mail system that encodesand stores a voice message intended for the recipient wireless telephoneuser.

Subsequently, the wireless telephone user can access the voice mailsystem to retrieve the message, at which time the message is decoded andsent to the BSC. At the BSC, the message is once again encoded, thensent to a base station for transmission to the wireless telephone. Uponreceipt of the message, the wireless telephone must once again decodethe message. Hence, in existing wireless telephone system voice mailsystems, a voice mail message undergoes two encoding/decoding cycles,once when the message is stored and again when the receiving personaccesses his or her voice mail. Unfortunately, the quality of the voicemessage is degraded as an undesirable consequence of multiple encodingsand decodings.

Accordingly, it is an object of the present invention to provide a voicemail system for a wireless telephone system which renders relativelyhigh quality voice mail messages. Another object of the presentinvention is to provide a voice mail system for a wireless telephonesystem which minimizes the number of encoding/decoding cycles voice mailmessages must undergo. Still another object of the present invention isto provide a voice mail system for a wireless telephone system which iseasy to use and cost-effective to manufacture and implement.

SUMMARY OF THE INVENTION

In a wireless telephone system including a base station controller(BSC), a base station, and at least one wireless telephone, a computerlogic device is disclosed which includes a computer logic storage devicereadable by a digital processing system. Instructions are embodied inthe logic storage device, and the instructions are executable by thedigital processing system for performing method steps for storing andrelaying voice messages. As disclosed in detail below, the method stepsinclude receiving a voice message at the BSC, wherein the voice messageis intended for a called telephone. When the called telephone does notpick up, if the message is not from a wireless telephone it is encodedand then stored at the BSC. Otherwise, i.e., if the message is fromanother wireless telephone and consequently is already encoded, themessage (after having been received and demodulated at the base stationtransceiver) is not decoded, and stored at the BSC.

Preferably, the method steps further include receiving a voice mailaccess call from an accessing telephone at the BSC. When the accessingtelephone is an accessing wireless telephone in the same system as theBSC, the voice message is retrieved from storage and transmitted to theaccessing wireless telephone without decoding the voice message at theBSC. Otherwise (i.e., when the accessing telephone is not in the BSCsystem, e.g., when the accessing telephone is a fixed telephone), thevoice message is retrieved from storage, decoded at the BSC, and sent tothe accessing telephone over a PSTN.

In a presently preferred embodiment, the digital modulation format iscode division multiple access (CDMA) format. Additionally, the methodsteps further include determining whether the called telephone is avoice mail subscriber, and storing the message only when the calledtelephone is a voice mail subscriber. The computer logic device is alsodisclosed in combination with the BSC.

In another aspect, a computer-implemented method is disclosed forstoring and relaying a voice message that has been generated in awireless telephone system. The method includes determining whether thevoice message should be stored, and if the voice message should bestored, storing the voice message. Then, the message is subsequentlyrelayed to an accessing telephone for playing back of the voice message.As envisioned by the present invention, the voice message undergoes atmost a single encoding/decoding cycle from when it is generated to whenit is played back.

In still another aspect, a wireless telephone system includes at leastone base station for receiving an incoming voice message transmitted bya sending telephone to a called telephone and for transmitting anoutgoing voice message to an accessing telephone. The system includes abase station controller (BSC) that is associated with the base station.Logic means are provided at the BSC for storing the incoming voicemessage in speech encoded format that is compatible with the wirelesscommunication system format when the called telephone does not pick up.Moreover, logic means at the BSC cause the voice message to betransmitted as the outgoing voice message in speech encoded format tothe accessing telephone when the accessing telephone is a wirelesstelephone. Furthermore, logic means at the BSC decodes the voice messageand then sends the voice message as the outgoing voice message to theaccessing telephone when the accessing telephone is not a wirelesstelephone in the BSC system.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a wireless telephone system forimplementing the voice message system of the present invention;

FIG. 2 is a flow chart showing the steps for receiving and storing avoice mail message; and

FIG. 3 is a flow chart showing the steps for retrieving and relayingvoice mail messages.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a digital wireless telephone system isshown, generally designated 10, which includes at least one base stationsystem, generally designated 12. As shown, the base station system 12includes a base station transceiver subsystem (BTS) 14 and an associatedbase station controller (BSC) 16. In accordance with well-knownprinciples, the BSC 16 controls plural BTS, although for clarity ofdisclosure only a single BTS 14 is shown in FIG. 1. The BTS 14 cancommunicate with at least first and second wireless telephones 18, 20via respective wireless links 22, 24. Furthermore, the BTS 14 cancommunicate with one or more non-system 10 telephones, such as aconventional fixed telephone 26, via a public switch telephone network(PSTN) 27.

The BTS 14 includes a modulator 14a for modulating waveforms to betransmitted in accordance with the modulation principles of the system10 (in the preferred embodiment, CDMA modulation principles). Similarly,the BTS 14 includes a demodulator 14b for demodulating receivedwaveforms in accordance with the demodulation principles of the system10.

Communication via the wireless links 22, 24 requires that messagestransmitted over the links 22, 24 be encoded in digital format andmodulated. Accordingly, each wireless telephone 18, 20 includesrespective encoding and decoding systems 30, 32 for converting voicesignals to digital format for transmission thereof to the BTS 14, andfor decoding signals from the BTS 14 to voice signals. In the presentlypreferred embodiment, the wireless air interface digital format is codedivision multiple access (CDMA) format. Accordingly, the preferredsystem 10 is a CDMA system, details of which can be found, for example,in U.S. Pat. Nos. 4,901,307 and 5,103,459, assigned to the same assigneeas is the present invention and incorporated herein by reference. Infurther accord with the preferred embodiment, the encoding/decodingsystems 30, 32 include respective vocoders, details of preferredembodiments of which are set forth in U.S. Pat. No. 5,414,796, assignedto the same assignee as is the present invention and incorporated hereinby reference.

FIG. 1 shows that the BSC 16 includes a vocoder including an encoder 34that receives packetized pulse code modulation (PCM) signals from thePSTN 27. The encoder 34 encodes the speech signal, it being understoodthat messages to be transmitted are modulated by the modulator 14a inthe BTS 14 after encoding as mentioned above. Also, the vocoder of theBSC 16 includes a decoder 38 that decodes demodulated CDMA signals fromthe demodulator 14b of the BTS 14. From the decoder 38, the signals aresent to the PSTN 27 (and, hence, the fixed telephone 26).

A microprocessor 42 communicates encoded signals to the modulator 14a ofthe BTS 14 via an outgoing communication link 44. Also, themicroprocessor 42 receives demodulated CDMA-formatted signals from theBTS 14 via an incoming communication link 46. Further, as shown in FIG.1 the microprocessor 42 communicates with the vocoder BSC encoder 34 andwith the BSC decoder 38. Moreover, the BSC 16 includes an electronicdata storage device 48 for storing data from the microprocessor 42, withthe data storage device being accessible by the microprocessor 42. Thedata storage device 48 can be any suitable device, e.g., a solid statememory device, hard disk drive, optical drive, or tape drive.

FIG. 1 also shows that the microprocessor 42 preferably includes aprogram storage device 50, which includes instructions that are used bythe microprocessor 42 to undertake the steps of the present invention.Accordingly, those skilled in the art will recognize that themicroprocessor 42 can include a programmable central processing unit(CPU), or a programmable gate array chip, or an application specificintegrated circuit (ASIC).

FIGS. 2 and 3 illustrate the structure of the logic of the presentinvention as embodied in computer-readable logic structures on thestorage device 50 (FIG. 1). Those skilled in the art will appreciatethat the Figures illustrate the structures of logic elements thatfunction according to this invention. Manifestly, the invention ispracticed in one essential embodiment by a machine component thatrenders the logic elements in a form that instructs a digital processingapparatus (that is, a computer or microprocessor) to perform a sequenceof operational steps corresponding to those shown in the Figures.

These instructions may reside in, i.e., be embodied by, logicstructures/circuits on a data storage device including a data storagemedium, such as the storage device 50 shown in FIG. 1. The machinecomponent shown in FIG. 1 is a combination of logic elements that areembodied in the storage device 50, which advantageously can beelectronic read-only memory (ROM) or electronic random access memory(RAM), or other appropriate data storage device. Alternatively, theinstructions can be embodied in the form of computer program codeelements on semiconductor devices, on magnetic tape, on optical disks,on a DASD array, on magnetic tape, on a conventional hard disk drive, orother appropriate data storage device.

Now referring to FIG. 2, the incoming call storage logic of the presentinvention can be seen. The BSC 16 receives an incoming call at block 52.The incoming call can be initiated from one of the wireless telephones18, 20 in the system 10, in which case the incoming call is sent fromthe BTS 14 to the BSC 16. Or, the incoming call can be initiated from anon-system 10 telephone, such as the fixed telephone 26, in which casethe call is received from the PSTN 27. The logic proceeds to decisiondiamond 54 to determine whether the called telephone (i.e., the"receiver") picked up.

If the called party has picked up, the logic moves to block 56 toconnect the originating telephone with the called telephone afterencoding the message if appropriate (i.e., when the call originated froma fixed telephone 26). On the other hand, if the called party has notpicked up, the logic proceeds to decision diamond 58 to determinewhether the called party is a voice mail subscriber of the BSC 16. Inmaking this determination, the microprocessor 42 can access a subscriberlist that is stored in the BSC 16. If the called party is not a voicemail subscriber of the BSC 16, the logic exits at state 60, but if thereceiver has not picked up and is a voice mail subscriber, the logicproceeds to decision diamond 62.

Decision diamond 62 represents the logic branches that are followed,based on the type of telephone that initiated the call. Specifically,when the incoming call is in CDMA format and, hence, was originated fromone of the wireless telephones 18, 20 in the system 10, the logic movesto block 64. At block 64, the message, having been demodulated whenreceived by the BTS 14, is not decoded prior to storage, but instead isstored in its encoded format. Thus, at block 66 the encoded message isstored in the data storage 48 (FIG. 1). On the other hand, if the callwas received from the PSTN 27, the logic moves to block 67, wherein thesignal is encoded by the vocoder 35. The encoded message is then storedat block 66.

FIG. 3 shows the process by which voice mail messages are retrieved fromthe BSC 16. Commencing at block 68, the BSC 16 receives a voice mailaccess call from one of the telephones 18, 20, 26. As was the case withdecision diamond 54 in FIG. 2, decision diamond 70 in FIG. 3 representsthe logic branches that are followed, based on the type of telephonethat initiated the access call.

When the accessing telephone is accessing via the PSTN 27, the logicmoves to block 72 to retrieve the voice mail message from the datastorage 48 and then to send the message to the decoder 38 of the BSC 16to decode the message. The decoded message is then sent to the fixedtelephone 26. Thus, a wireless telephone user can access his or hervoice mail using a fixed telephone or other non-system 10 wirelesstelephone, if desired.

Alternatively, the user can access his or her voice mail using one ofthe wireless telephones 18, 20, in which case the logic moves fromdecision diamond 70 to block 76. At block 76, the encoded message isretrieved from the data storage 48, sent to the BTS 14 and modulated bythe modulator 14b of the BTS 14, and then transmitted in CDMA format tothe accessing wireless telephone 18, 20. At block 78, the accessingwireless telephone 18, 20 demodulates and decodes the message to a voicesignal.

With the above disclosure in mind, it can now be appreciated that a callcan be placed by a wireless telephone 18, 20 or a fixed telephone 26,for receipt thereof by a wireless telephone 20, 18. In the event thatthe called wireless telephone 20, 18 does not pick up, the call can bestored as a voice mail message at the BSC 16. Then, the user of thecalled wireless telephone 20, 18 can access the voice mail message froma wireless telephone 20, 18 or from a fixed telephone 26 to retrieve themessage. Regardless of the type of telephone that initiated the voicemail message, and regardless of the type of telephone that retrieves themessage, the message undergoes only a single encoding/decoding cyclefrom the time it is generated to the time it is listened to by a user,thereby improving the quality of the message, compared to voice mailsystems wherein messages might undergo several encoding/decoding cycles.As used herein, the terms "encoding" and "decoding" refer to vocodingprocesses, i.e., the processes undertaken in a wireless telephone systemto convert a voice-formatted message to a digital message and backagain, using a vocoder.

While the particular INTEGRATED VOICE MAIL SYSTEM FOR CDMA NETWORK asherein shown and described in detail is fully capable of attaining theabove-described objects of the invention, it is to be understood that itis the presently preferred embodiment of the present invention and isthus representative of the subject matter which is broadly contemplatedby the present invention, that the scope of the present invention fullyencompasses other embodiments which may become obvious to those skilledin the art, and that the scope of the present invention is accordinglyto be limited by nothing other than the appended claims.

What is claimed is:
 1. In a wireless telephone system including a basestation controller (BSC) and a plurality of wireless telephones, acomputer logic device comprising:a computer logic storage devicereadable by a digital processing system; and instructions embodied inthe logic storage device, the instructions being executable by thedigital processing system for performing method steps for storing andrelaying voice messages, the method steps comprising: receiving a voicemessage at the BSC, the voice message being intended for a calledtelephone; when the called telephone does not pick up, if the message isfrom a wireless telephone in the system, storing the message withoutfurther encoding or decoding of the message, and otherwise encoding themessage and then storing the message at the BSC.
 2. The computer logicdevice of claim 1, wherein the method steps further comprise:receiving avoice mail access call from an accessing telephone at the BSC; when theaccessing telephone is an accessing wireless telephone in the system,retrieving the voice message from storage and transmitting the voicemail to the accessing wireless telephone without decoding the voicemessage at the BSC; otherwise retrieving the voice message from storage,decoding the voice message at the BSC, and sending a modulated versionof the voice message to the accessing telephone.
 3. The computer logicdevice of claim 2, wherein the message is transmitted to the accessingwireless telephone in code division multiple access (CDMA) format. 4.The computer logic device of claim 3, wherein the method steps furthercomprise:determining whether the called telephone is a voice mailsubscriber; and storing the message only when the called telephone is avoice mail subscriber.
 5. The computer logic storage device of claim 4,in combination with the BSC.
 6. A wireless telephone system including atleast one base station for receiving an incoming voice messagetransmitted by a sending telephone to a called telephone and fortransmitting an outgoing voice message to an accessing telephone,comprising:a base station controller (BSC) associated with the basestation; logic means at the BSC for storing the incoming voice messagein encoded format when the called telephone does not pick up; logicmeans at the BSC for causing the voice message to be transmitted as theoutgoing voice message in encoded format to the accessing telephone whenthe accessing telephone is a wireless telephone in the system; and logicmeans at the BSC for decoding the voice message from CDMA format andthen sending the voice message as the outgoing voice message to theaccessing telephone when the accessing telephone is not a wirelesstelephone in the system.
 7. The system of claim 6, furthercomprising:logic means at the BSC for encoding the voice message whenthe incoming voice message is not from a wireless telephone in thesystem, prior to storing the voice message.
 8. The system of claim 7,further comprising:logic means at the BSC for receiving a voice mailaccess call from an accessing telephone; logic means at the BSC for,when the accessing telephone is an accessing wireless telephone in thesystem, retrieving the voice message from storage and transmitting thevoice mail to the accessing wireless telephone without decoding thevoice message at the BSC; and logic means at the BSC for, when theaccessing telephone is not an accessing wireless telephone in thesystem, retrieving the voice message from storage, decoding the voicemessage at the BSC, and sending the voice message to the accessingtelephone.
 9. A computer-implemented method for storing and relaying avoice message intended for a called telephone, the voice message havingbeen generated in a wireless telephone system, comprising the stepsof:determining whether the voice message should be stored; if the voicemessage should be stored, storing the voice message and subsequentlyrelaying the voice message to an accessing telephone for playing back ofthe voice message, such that the voice message undergoes at most asingle encoding/decoding cycle from when the voice message is generatedto when the voice message is played back; and if the voice message isnot generated by a wireless telephone in the system, encoding the voicemessage and then storing the voice message at a base station controller(BSC), and otherwise storing the voice message at the BSC withoutdecoding the voice message, wherein the determining step comprises thesteps of:determining whether the called telephone picks up; when thecalled telephone does not pick up, determining whether the calledtelephone is a voice mail subscriber; and determining that the voicemessage should be stored when the called telephone is a voice mailsubscriber.
 10. The computer-implemented method of claim 9, furthercomprising the steps of:receiving a voice mail access call from anaccessing telephone at the BSC; when the accessing telephone is anaccessing wireless telephone in the system, retrieving the voice messagefrom storage and transmitting the voice mail message to the accessingwireless telephone without decoding the voice message at the BSC; andwhen the accessing telephone is not an accessing wireless telephone inthe system, retrieving the voice message from storage, decoding thevoice message at the BSC, and sending the voice message to the accessingtelephone.
 11. The computer-implemented method of claim 10, wherein themessage is transmitted to a wireless telephone in code division multipleaccess (CDMA) format.
 12. The computer-implemented method of claim 11,in combination with the BSC.